Friction-brake.



No. 69I,5l3. Patented lan. 2|, |902.

F. L. WHITMORE.

. FBICTION BRAKE.

(Application led July `26, 1901.)

4 Sheets-Sheet I.

(No Model.)

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No. 69I,5I3. Patented lan. 2l, |902.

F. L. WHITMORE.

FRICTIUN BRAKE.

vApplication filed July 26, 1901.1

4 Sheets-Sheet 3.

me -owns Pinzas co, FHoYmUmo.. msumm'on. n. c.

No. 691,513. Patented lan. 21, |902.

F. L. WHITMORE.

vFmclorl'nAula.l

(Application led July 26, 1901.) (No Model.) 4 Sheets-Sheet 4.

flrRAsit BTENT rrrcs.'

` ,/r) il'. I iE NA"-4 YXI'HTMORE, OF BELVEDERE, ENGLAND.

FRlOTiON-BRAKE.

SPECIFICATIO forming part of Letters Patent No. 691,513, dated January 21, 1902.

Application filed July 26,1901.

T0 all whom, t may concern.

Be it known that I, FRANK LEONARD WHIT- MORE, a subject of the King of Great Britain, residing at Belvedere, in the county of Kent, England, have invented a new and useful Improvement in Friction-Brakes, of which the following is a specification.

This invention relates to an improvement in friction-brakes, particularly of the class used for heavy work, such as brakes for the drums of winding and hauling machinery; but it is applicable also for brakes of a lighter class applied to rotating parts of various inachines.

The invention consists of an arrangement of springs (or of a plunger working in an airtight cylinder) inserted between the weight that applies the brake and the brake itself, so that the connection between the two shall not be a rigid one, the motive power being applied to the brake through the medium of the said springs or cylinder and a distancepiece, which comes into action after the springs are (or the air in the cylinder has been) compressed by the weight to any desired extent, so as to form a rigid connection between the Weight and the brake, and with this is employed an arrangement of mechanism which automatically takes up the wear of the brake-blocks as fast as such wear occurs.

In the accompanying drawings, Figure 1 is an elevation of a brake constructed in accordance with the invention. Fig. 19 is an elevation, partly in section, showing the construction of the brake-engine. Fig. 2 is a sectional elevation on line X X of Fig. 1. Fig. 3 is a plan. Fig. 4 is a detail on an enlarged scale, showing a modiiication. Fig. 5 is an elevation of the arrangement as applied to a bandbrake, Vand Fig. 6 is a plan of a part of Fig. 5.

The brake-gear (see Fig. 1) consists of a Vbrake-engine 1to the cross-head of which is suspended a weight 2 by means of the rod 3, which passes through the spring-box 4, the bottom of which rests on the end of lever 5 and the spring being compressed between the bottom of box 4 and washer 6 on rod 3. The

lever 5 is centrally pivoted at 12 and is connected up to the two brake-beam levers 7 8 by connecting-rods 13 14, so that a downward movement of lever 5 applies the brakes 9 9 and an upward movement releases them, the

Serial No. 69.862. (No model.)

twobrakes for this purposev being connected by rods 15 16. A distance-piece or sleeve 10 of suitable length is iitted around rod 3 in the box 4, so that until the washer 6 comes in contact with it the load is applied to the brakes through the spring; but as soon as the washer 6 reaches the said distance-piece 10 the load is applied by the weight 2. On the rod 3, below the lever 5, is iixed a collar 18.

The brake-engine 1 is of the usual type/and, as shown in Fig; 1a, consists of a steam-cylinder and a cataract-cylinder 5l, the pistons of the two being connected by a rod 51a, which is also connected to the cross-head 52. vThe steam-cylinder is single-acting,steam being admitted only to the under side of the piston to lift the weight 2 and release the brake. The cataract-cylinder has a by-pass valve 53, which when closed locks the piston, and consequently also the weight, in any position, and when open admits of a free passage from one side of the piston to the other. Y54is the steam inlet and exhaust valve for the cylinder 50, and 55 the exhaust-pipe. At some point on the cylinder is pivoted a bell-crank lever, (indicated at 56,) and the valves 54 and 53 are also provided with levers, (indicated at 57 y and 5S, respectively.) Lever 56 carries a floating lever, (indicated at 60,) one end of which is connected to a rod, (indicated by 59,) which also connects levers 57 and 58, and the other end of lever 60 is connected by a rod (indicated at 6l) to cross-head 52. The operation of these parts is as follows: The point E of bell-crank lever 56 corresponds in its position to the position of the hand-lever 17, Fig. l, as it is connected to it by the arrangement of bell-crank and levers shown in that igure. Now supposing the pistons are in the top position, the pointE of lever 56 will be over toward the cylinder, with the point F, which indicates the other end of the lever, at its top position, and point G, which indicates the end of lever 60, at its top position, the points H, I, and J, which indicate the ends of levers 60, 57, and 58,respectively,being,with the valves, in the position shown. Suppose the driver now brings his lever 17 to a central position, the points E and F will come into the central position, which operation will lower the position of H, I, and J, opening the valve 54 for steam to exhaust and opening the valve 53 IOO of the cataract-cylinder from one side of the piston to the other. When this takes place, the weight brings down the pistons and with them point G of lever GO, which pivots on point F, thus raising again points H I .I to the position shown, and so closing the valves, this operation corresponding to any position required.

In place of the arrangement of steam and cataract cylinders described a single cylinder having two pistons may be used; lbut neither of these constructions forms part of my invention.

It should be noted that for every position of the hand-lever there is a corresponding position of the brakeengine piston and crosshead due to the action of the fioating lever, which is connected to the cross-head. This action and the construction of the engine above described are of course quite common in brake-engines, and it forms no part of the present invention.

Now suppose the maximum stroke of the brake-engine is sixteen inches and the brake is ofthe hand-lever (indicated at 17) willbein position A, the brake-engine at the top of its stroke, and the lever 5 will be held up against the bottom of spring-box 4 by the collar 1S.

Now the stroke of the brake-engine can be divided into threedistinct periods. The first period will include about the first four inches of the down or working stroke of the piston, and during this time the clearance between the brake-blocks 9 9 and the drum would be taken up, so that at the end ofthe first period the block would be up against the drum and the hand-lever 17 would be in about position B. The second period will include about the next eight inches of the stroke. During this period the springs will be compressed by the weight 2 and will tend to force the lever 5 farther down and the brake-blocks up against the drum, thus applying the brake. The length of the distance-piece or sleeve 10 must be fixed so that at the end of this period the washer G will .be just resting on it and the hand-lever will be in about position C. It should also be noticed that during this period a varying load may be applied to the brake corresponding to the position of-the hand-lever. The third period will include about the last four inches of the stroke. At the end of the second period the washer 6 will be resting on the distance-piece 10, as stated above, and therefore during this third period there will be a rigid connection between the weight 2 and lever 5-that is to say, when the weights move down oneinch the end of lever must also move down one inch. This last period is included for safety i n`case,due to broken springs or other causes, the brake has not held the load by the end of the second period. At the end of the third period the hand-lever would be in position D.

During the release or upstroke of the engine the reverse action takes place and the lever 5 is finally moved back to itsoriginal position by the collar 1S coming in contact with the under side of the lever and moving it up with it, thus moving the brake-blocks back clear of the drum. In a hoist fitted with an overwinding safety-gear, which comes into action in case of overwinding and applies all the brakes suddenly, this use of the springs is oi great advantage, as they greatly reduce the shock of the weight suddenly falling, and thus decrease the chance of breaking any of the gear.

Instead of the arrangement of springs working in a spring-box a dash-pot 2O (see Fig. 4) can be used, the plunger 21 being connected to the Weight 2 by rods 22 22, so that as the weight falls the air, gas, or other vapor in the dash-pot is compressed, thus applying the brake during the second period. At the end of this period the plunger 21 would come down onto a stop and the whole dead-weight be applied, as in the case of the springs described above. A valve wouldbe arranged in the bottom of the dash-pot to admit the air, gas, or other vapor on the upstroke of the plunger in case the compressed air, gas, or Vapor should haveleaked past the plunger, which might happen if the brake were kept full on for anylong period. In this case the nuts 23 23 on therrods 22 22 take the place of the collar 18, the adjustment being got up by altering the lengths of the rods 22.

It is of course essential for the safe Working of the brake that the blocks 9 9 should not be too far off the drum when the brake is right off, as, if they are, too great a proportion of the brake-engine stroke would be required to take up the clearance; but owing to the wear ot' the blocks this clearance will go on increasing until such time as the brakeblocks are restored by hand to give their original amount of clearance. This is a source of danger and is present in nearly all kinds of friction brakes, as excessive wear of the blocks or neglect in adjusting them when required lnight easily prevent the brakes from acting even with the brake-engine at the bottom of its stroke'. To remedy this defect, the automatic take-up mechanism has been designed. Figs. 1, 2, and 3 show this mechanism applied to double friction-brakes of the post or beam type, while Figs. 5 and 6 show it applied to a friction-brake of the band type.

The rods 15 '16, (see Figs. l, 2, and 3,)

which connect the two brakes together, are

screwed at one end and are each fitted with ICO IIO

a nut in the form of a'ratchet-wheel 25, which 2S are connected by the vertical rod 29, and the lower one is also connected by a short link 30 to a crank 3l of a shaft 32 in such a way that the link 30 is free to slide longitudinally on the crank. The shaft 32 is carried in bearings 34, and to its end is attached a lever 35, through the end of which passes a rod 36, which is carried on the lever 5 and receives its motion from the same. The rod 36 is also fitted with two movable stops 37 37, which may be adjusted in any desired position. ratchet-wheels 25 25 as they are screwed up. Now as long as the brakes are properly adjusted' on applying them the end of lever 5 will only need to move down about four inches-that is to'say, to the end of the rst period, as described above-when the brakeblocks will come up against the drum; but as the blocks wear the lever 5 will have to move lower and lower down before this happens. Now the upper of the two stops 37 is adjusted so that after the lever 5 has moved down any desired amount such stop 37 comes in contact with the upper face of the lever 35, thus moving the shaft 32 and with it the crank 3l, the link 30, rod 29, and the arms 28 28, all these moving in a downward direction. This allows the pawls 27 to take up another tooth or teeth'of the ratchet-wheels 25 25. Now when the brake is released and the lever 5 rises the lower of the two stops 37 comes up against the lever 35 and brings it back again to its original position. The arms 28 are now moved upward and the pawls turn the ratchet-wheels, thus screwing up the nut and bringing the brake-blocks up nearer together-in other words,automatically taking up the wear of the block as this occurs. As the ratchet-nuts 25 are gradually screwed along the rods 15 16 they carry with them the rod 29 and link 30. Hence the necessity for the sliding movement of the link 30 on crank 3l. Other arrangements of the details of this mechanism may, however, be employed, and it will be understood that the invention can be readily adapted to other types of post or pivoted brakes.

In the friction-brake of the band type (see Figs. 5 and 6) the rod 40,connecting the band 4l to the head 42, has a right and left hand thread engaging with each of these parts, respectively, and the head 42 is pivoted to the lever 8. The ratchet-wheel 25 is fixed to rod 40 and is operated by a pawl 27, carried on swinging arms 43, which in turn is connected by the rod 44 to one end of a lever 45, which pivots on the same center as the main brakelever 8. This lever 45 is connected at the The xed spring-pawls 38 38 lock the other end to the lever 8 by means of the rod 46, which passes through an eye in the end of lever 45, two adjustable stops 47 47 being carried by rod 46, as in the other brake. The fixed spring-pawl 38 locks the ratchet-wheel as it is screwed up. The action of the takeup is the same as the one described above, the -screwed rod 40 drawing the brake-band 4l nearer to the head 42 as it is operated.

It will be understood that many of the parts above described may be substituted by others without altering the nature of the invention.

l. Inabrake, the combination withasource of power for operating same, and the brakeblock, of a lever and parts connected therewith and with said block, a rod operated by the source of power and passing freelythrough such lever, a xed part on said rod, a spring interposed between such fixed part and the lever so that the rod is moved rst under spring-pressure and a distance-piece surrounding said rod, and against which the fixed part carried by same abuts after a certain point of .compression of the spring has been reached so that the lever will be moved positively by the operating means.

2. In a brake, the combination with the brake-block and a lever for applying same, of a rod attached to the brake-block at one end, means for holding the rod at the other end, a screwed end to such rod, a nut into which such screwed end is inserted, a ratchetwheel for traversing said screwed end in such nut, a pawl for operating such ratchet and means controlled by the brake-lever for moving such pawl only after an excessive movement of the brake-lever.

3. In a brake, the combination with the brake-block and a lever for applying same, of means for compensating for wear of the block by moving same nearer to the surface it is acting upon, a lever through which such compensating means are operated, a rod connected to the brake-lever and passing freely through the lever operating the compensating means and a stop on such rod whereby it is brought into action only after an excessive movement of the brake-lever.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

FRANK' LEONARD WHITMORE.

Witnesses:

FRED C. HARRIS, WALTER J. SKERTEN.

IOO 

